The second golf major of 2020 is underway at Winged Foot Golf Club, and it is expected to be one of the toughest challenges each player in the field faces this calendar year. 

A handful of players that started in the morning threesomes have posted under-par scores, including Rory McIlroy, but there is a much larger number of golfers over par in the first few hours of U.S. Open play. 

Tournament favorites Dustin Johnson and Jon Rahm are slated to tee off during the afternoon session. Johnson, who won the FedEx Cup two weeks ago, will play alongside Bryson DeChambeau and Tony Finau.

Rahm will be playing with Paul Casey and Phil Mickelson. Mickelson is one of 16 golfers to play Winged Foot at the 2006 U.S. Open, where he finished second to Geoff Ogilvy.

US Open Leaderboard

Davis Thompson (-2)

Rory McIlroy (-2)

Brian Harman (-1)

Brandon Wu (-1)

J.T. Poston (-1)

Harris English (-1)

Jason Kokrak (-1)

Paul Waring (-1)

Tyrrell Hatton (-1)

Justin Rose (-1)

Lucas Glover (-1)

Charles Howell III (-1)

Corey Conners (-1)

Robert MacIntyre (-1)

Hideki Matsuyama (-1)

Dan McCarthy (-1)

Scoring update as of 9:45 a.m. ET.

Full leaderboard can be found on PGATour.com.

McIlroy has had the most success from the early wave of golfers out on the course. The Northern Irishman picked up birdies in two of his first four holes after teeing off on the 10th hole. 

The 31-year-old has been a fixture in the top 10 of majors in recent years, but he has not won one since the 2014 PGA Championship. 

McIlroy shared the lead at one point with Brandon Wu, who carded three birdies after a bogey at No. 3. Wu owns the most birdies of any player currently out on course, and there is a chance he holds that title for a decent while. 

Amateur Davis Thompson also reached two-under on the front nine with back-to-back birdies at the sixth and seventh holes. 

The majority of the players at one-under have a collection of pars with a birdie sprinkled in between. Tyrrell Hatton is the exception to that, as he birdied his first two holes before giving a shot back to the course. 

Tiger Woods played with a steady hand at the beginning of his round with three pars over three holes, but he dropped a shot at No. 4 to join the growing list of players over par. 

Sergio Garcia and Patrick Cantlay are among the golfers who have struggled out of the gates at Winged Foot.

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